Communication systems utilizing radio frequency (RF) signals often convert the received signal into an in-phase (I) component and a quadrature (Q) component. A mismatch in the electrical components in these signal channels causes I/Q amplitude and phase imbalances in the received signal. I/Q imbalance algorithms implemented within the digital processing parts of a receiver can be used to estimate these amplitude and phase imbalances, however, they rely for their accuracy on a strong static received carrier signal. Under weak carrier signal reception, the accuracy of these I/Q imbalance estimates is reduced because of the presence of increased noise in the I/Q data. This noise leads to errors in the I/Q imbalance estimations and hence the correction applied to the received signal, and this is especially pronounced where the signal is converted into its constituent baseband I/Q components such as in direct conversion receivers; for example, in analog frequency modulation (FM) transceivers.
Furthermore, because the carrier signal used to estimate the I/Q imbalance needs to be static, the overall communications system of transmitters and receivers requires a scan mode which reduces the traffic bandwidth of the system and requires complicated control systems to coordinate these periodic scan modes.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.